/*
 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.naming;

import java.util.Vector;
import java.util.Enumeration;

/**
 * This class represents a reference to an object that is found outside of
 * the naming/directory system.
 * <p>
 * Reference provides a way of recording address information about
 * objects which themselves are not directly bound to the naming/directory system.
 * <p>
 * A Reference consists of an ordered list of addresses and class information
 * about the object being referenced.
 * Each address in the list identifies a communications endpoint
 * for the same conceptual object.  The "communications endpoint"
 * is information that indicates how to contact the object. It could
 * be, for example, a network address, a location in memory on the
 * local machine, another process on the same machine, etc.
 * The order of the addresses in the list may be of significance
 * to object factories that interpret the reference.
 * <p>
 * Multiple addresses may arise for
 * various reasons, such as replication or the object offering interfaces
 * over more than one communication mechanism.  The addresses are indexed
 * starting with zero.
 * <p>
 * A Reference also contains information to assist in creating an instance
 * of the object to which this Reference refers.  It contains the class name
 * of that object, and the class name and location of the factory to be used
 * to create the object.
 * The class factory location is a space-separated list of URLs representing
 * the class path used to load the factory.  When the factory class (or
 * any class or resource upon which it depends) needs to be loaded,
 * each URL is used (in order) to attempt to load the class.
 * <p>
 * A Reference instance is not synchronized against concurrent access by multiple
 * threads. Threads that need to access a single Reference concurrently should
 * synchronize amongst themselves and provide the necessary locking.
 *
 * @author Rosanna Lee
 * @author Scott Seligman
 * @see RefAddr
 * @see StringRefAddr
 * @see BinaryRefAddr
 * @since 1.3
 */

  /*<p>
  * The serialized form of a Reference object consists of the class
  * name of the object being referenced (a String), a Vector of the
  * addresses (each a RefAddr), the name of the class factory (a
  * String), and the location of the class factory (a String).
*/


public class Reference implements Cloneable, java.io.Serializable {

  /**
   * Contains the fully-qualified name of the class of the object to which
   * this Reference refers.
   *
   * @serial
   * @see java.lang.Class#getName
   */
  protected String className;
  /**
   * Contains the addresses contained in this Reference.
   * Initialized by constructor.
   *
   * @serial
   */
  protected Vector<RefAddr> addrs = null;

  /**
   * Contains the name of the factory class for creating
   * an instance of the object to which this Reference refers.
   * Initialized to null.
   *
   * @serial
   */
  protected String classFactory = null;

  /**
   * Contains the location of the factory class.
   * Initialized to null.
   *
   * @serial
   */
  protected String classFactoryLocation = null;

  /**
   * Constructs a new reference for an object with class name 'className'.
   * Class factory and class factory location are set to null.
   * The newly created reference contains zero addresses.
   *
   * @param className The non-null class name of the object to which this reference refers.
   */
  public Reference(String className) {
    this.className = className;
    addrs = new Vector<>();
  }

  /**
   * Constructs a new reference for an object with class name 'className' and
   * an address.
   * Class factory and class factory location are set to null.
   *
   * @param className The non-null class name of the object to which this reference refers.
   * @param addr The non-null address of the object.
   */
  public Reference(String className, RefAddr addr) {
    this.className = className;
    addrs = new Vector<>();
    addrs.addElement(addr);
  }

  /**
   * Constructs a new reference for an object with class name 'className',
   * and the class name and location of the object's factory.
   *
   * @param className The non-null class name of the object to which this reference refers.
   * @param factory The possibly null class name of the object's factory.
   * @param factoryLocation The possibly null location from which to load the factory (e.g. URL)
   * @see javax.naming.spi.ObjectFactory
   * @see javax.naming.spi.NamingManager#getObjectInstance
   */
  public Reference(String className, String factory, String factoryLocation) {
    this(className);
    classFactory = factory;
    classFactoryLocation = factoryLocation;
  }

  /**
   * Constructs a new reference for an object with class name 'className',
   * the class name and location of the object's factory, and the address for
   * the object.
   *
   * @param className The non-null class name of the object to which this reference refers.
   * @param factory The possibly null class name of the object's factory.
   * @param factoryLocation The possibly null location from which to load the factory (e.g. URL)
   * @param addr The non-null address of the object.
   * @see javax.naming.spi.ObjectFactory
   * @see javax.naming.spi.NamingManager#getObjectInstance
   */
  public Reference(String className, RefAddr addr,
      String factory, String factoryLocation) {
    this(className, addr);
    classFactory = factory;
    classFactoryLocation = factoryLocation;
  }

  /**
   * Retrieves the class name of the object to which this reference refers.
   *
   * @return The non-null fully-qualified class name of the object. (e.g. "java.lang.String")
   */
  public String getClassName() {
    return className;
  }

  /**
   * Retrieves the class name of the factory of the object
   * to which this reference refers.
   *
   * @return The possibly null fully-qualified class name of the factory. (e.g. "java.lang.String")
   */
  public String getFactoryClassName() {
    return classFactory;
  }

  /**
   * Retrieves the location of the factory of the object
   * to which this reference refers.
   * If it is a codebase, then it is an ordered list of URLs,
   * separated by spaces, listing locations from where the factory
   * class definition should be loaded.
   *
   * @return The possibly null string containing the location for loading in the factory's class.
   */
  public String getFactoryClassLocation() {
    return classFactoryLocation;
  }

  /**
   * Retrieves the first address that has the address type 'addrType'.
   * String.compareTo() is used to test the equality of the address types.
   *
   * @param addrType The non-null address type for which to find the address.
   * @return The address in this reference with address type 'addrType; null if no such address
   * exist.
   */
  public RefAddr get(String addrType) {
    int len = addrs.size();
    RefAddr addr;
    for (int i = 0; i < len; i++) {
      addr = addrs.elementAt(i);
      if (addr.getType().compareTo(addrType) == 0) {
        return addr;
      }
    }
    return null;
  }

  /**
   * Retrieves the address at index posn.
   *
   * @param posn The index of the address to retrieve.
   * @return The address at the 0-based index posn. It must be in the range [0,getAddressCount()).
   * @throws ArrayIndexOutOfBoundsException If posn not in the specified range.
   */
  public RefAddr get(int posn) {
    return addrs.elementAt(posn);
  }

  /**
   * Retrieves an enumeration of the addresses in this reference.
   * When addresses are added, changed or removed from this reference,
   * its effects on this enumeration are undefined.
   *
   * @return An non-null enumeration of the addresses (<tt>RefAddr</tt>) in this reference. If this
   * reference has zero addresses, an enumeration with zero elements is returned.
   */
  public Enumeration<RefAddr> getAll() {
    return addrs.elements();
  }

  /**
   * Retrieves the number of addresses in this reference.
   *
   * @return The nonnegative number of addresses in this reference.
   */
  public int size() {
    return addrs.size();
  }

  /**
   * Adds an address to the end of the list of addresses.
   *
   * @param addr The non-null address to add.
   */
  public void add(RefAddr addr) {
    addrs.addElement(addr);
  }

  /**
   * Adds an address to the list of addresses at index posn.
   * All addresses at index posn or greater are shifted up
   * the list by one (away from index 0).
   *
   * @param posn The 0-based index of the list to insert addr.
   * @param addr The non-null address to add.
   * @throws ArrayIndexOutOfBoundsException If posn not in the specified range.
   */
  public void add(int posn, RefAddr addr) {
    addrs.insertElementAt(addr, posn);
  }

  /**
   * Deletes the address at index posn from the list of addresses.
   * All addresses at index greater than posn are shifted down
   * the list by one (towards index 0).
   *
   * @param posn The 0-based index of in address to delete.
   * @return The address removed.
   * @throws ArrayIndexOutOfBoundsException If posn not in the specified range.
   */
  public Object remove(int posn) {
    Object r = addrs.elementAt(posn);
    addrs.removeElementAt(posn);
    return r;
  }

  /**
   * Deletes all addresses from this reference.
   */
  public void clear() {
    addrs.setSize(0);
  }

  /**
   * Determines whether obj is a reference with the same addresses
   * (in same order) as this reference.
   * The addresses are checked using RefAddr.equals().
   * In addition to having the same addresses, the Reference also needs to
   * have the same class name as this reference.
   * The class factory and class factory location are not checked.
   * If obj is null or not an instance of Reference, null is returned.
   *
   * @param obj The possibly null object to check.
   * @return true if obj is equal to this reference; false otherwise.
   */
  public boolean equals(Object obj) {
    if ((obj != null) && (obj instanceof Reference)) {
      Reference target = (Reference) obj;
      // ignore factory information
      if (target.className.equals(this.className) &&
          target.size() == this.size()) {
        Enumeration<RefAddr> mycomps = getAll();
        Enumeration<RefAddr> comps = target.getAll();
        while (mycomps.hasMoreElements()) {
          if (!(mycomps.nextElement().equals(comps.nextElement()))) {
            return false;
          }
        }
        return true;
      }
    }
    return false;
  }

  /**
   * Computes the hash code of this reference.
   * The hash code is the sum of the hash code of its addresses.
   *
   * @return A hash code of this reference as an int.
   */
  public int hashCode() {
    int hash = className.hashCode();
    for (Enumeration<RefAddr> e = getAll(); e.hasMoreElements(); ) {
      hash += e.nextElement().hashCode();
    }
    return hash;
  }

  /**
   * Generates the string representation of this reference.
   * The string consists of the class name to which this reference refers,
   * and the string representation of each of its addresses.
   * This representation is intended for display only and not to be parsed.
   *
   * @return The non-null string representation of this reference.
   */
  public String toString() {
    StringBuffer buf = new StringBuffer("Reference Class Name: " +
        className + "\n");
    int len = addrs.size();
    for (int i = 0; i < len; i++) {
      buf.append(get(i).toString());
    }

    return buf.toString();
  }

  /**
   * Makes a copy of this reference using its class name
   * list of addresses, class factory name and class factory location.
   * Changes to the newly created copy does not affect this Reference
   * and vice versa.
   */
  public Object clone() {
    Reference r = new Reference(className, classFactory, classFactoryLocation);
    Enumeration<RefAddr> a = getAll();
    r.addrs = new Vector<>();

    while (a.hasMoreElements()) {
      r.addrs.addElement(a.nextElement());
    }
    return r;
  }

  /**
   * Use serialVersionUID from JNDI 1.1.1 for interoperability
   */
  private static final long serialVersionUID = -1673475790065791735L;
};
